Well, my three brothers and I ranged from ages 5 to 10, so that's a good starting point. Then figure it's a bunch of long narrow hallways, which were wide enough for kids to run in, but narrow enough that you feel fast running along the walls. Low-pile office park carpet turns out to be perfect for traction when running in your socks at that age. And then M&Ms and vending machine stuff is the perfect treat for kids who mostly ate homemade meals.

I'm sure the two most uncommon enablers of the good experience were 1, there being four kids in the family to play together and, 2, my dad not worrying that we were going to cause a bunch of problems when left to run around the office.